Experimental Study On Hydrodynamic Characteristics Of Curved Section Of The Spillway Chute With The Diversion Wall

It is adopted in recent years to set the diversion wall on the axis of the bend to improve the flow condition of the bend.This method can effectively reduce the surface difference in the cross section of the bend,make the flow evenly distributed,reduce the height of the side wall,and save the investment,facilitate the construction,so it has a great application prospect.In this paper,the hydraulic experiments of 27 schemes of different bend radius(R=1200,1600,2000mm),different bottom slope(i=0.005,0.01,0.02)and different flows(Q=50,100,150m~3/h)were carried out.Using the model experimental data,combining theoretical analysis with statistical analysis,the distribution characteristics of water depth,flow velocity and dynamic water pressure after setting the diversion wall are studied.The main research results include:(1)In this paper,through the analysis of influence of bottom slope,radius,and flows on the concave depth,convex depth and maximum surface difference of cross section,draw their change regulations with various influencing factors.The analysis shows that the maximum water surface difference occurs mainly in the vicinity of the middle of the bend when the flow of the bend is slow-flow,and the maximum water surface difference occurs mainly in the tail section of the bend when the bend flow is the torrent.Through the analysis of the influence factors of maximum surface difference correction coefficient and the regression analysis,the calculation formula of the maximum surface difference correction coefficient under the condition of the diversion wall is obtained.(2)Through the analysis of three-dimensional velocity data,the distribution law of longitudinal velocity,transverse velocity and turbulent intensity along the path,cross section and vertical line under the condition of slow-flow,torrent,with and without diversion wall is obtained.Through the analysis of the influence of the bottom slope and the radius on the longitudinal velocity and the transverse velocity,it is found that with the increase of the radius or with the decrease of the bottom slope,the longitudinal velocity decreases,the transverse velocity redistribution promotes the flow from the concave to convex trend,weaken the trend of flow from the convex to concave.Therefore,increasing the radius and reducing the bottom slope can smooth the flow and reduce the influence of the circumfluence of the bend.(3)Through the dynamic water pressure analysis,it is found that the vertical distribution of the time average pressure is followed by the hydrostatic pressure,but there is a certain difference.When calculating water pressure,in order to ensure the safety of the wall structure,after comprehensive consideration,concave and convex side wall and the guide wall of the left and right sides of the bottom end of the mean pressure should be the hydrostatic pressure110%,120%,115%,115%.The pulsating pressure characteristics of the side wall and the floor of the bend are analyzed from the waveform,intensity and frequency domain of the pulsating pressure.It is found that the process of water pulsation belongs to a random process of stationary ergodic.The fluctuating pressure and intensity are relatively small,and the dominant frequency of flow pulsation is small,which belongs to low-frequency vibration,and doesn't produce resonance damage.